PTCH1 and skin cancer: Abnormal HH signaling can be found in cancer of the skin, brain, liver, prostate and breast; in malignant blood disease; etc. [6].The canonical HH signaling pathway molecules includes Hedgehog ligands (Sonic hedgehog, Indian hedgehog and Desert hedgehog), PTCH (PTCH-1 and PTCH-2), Smoothened and GLIs (GLI-1, GLI-2 and GLI-3).